Field enhanced luminescence system



July 11, 1961 D. A. CUSANO 2,992,349

FIELD ENHANCED LUMINESCENCE SYSTEM Filed Oct. 24, 1957 Fig.

Brig/7 mess Raf/'0 Curie"! D (m/cro amperes per sq cm) Inventor Dom/hieA. Cusano,

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United States Patent 2,992,349 FIEL D ENHANCED LUMINESCENCE SYSTEMDominic A. Cnsano, Schenectady, N. assignor to General Electric Company,a corporation of New York Filed Oct. 24, 1957, Ser. No. 692,211 6Claims. (Cl. 313-92) The present invention pertains to informationportraying devices and systems, and more particularly to such devicesand systems in which information or intelligence carried by cathode raysis reproduced and intensified within a screen comprising a solidluminescent material.

It is well known that luminescent solids may be excited to luminescenceby the incidence of cathode rays. In formation portraying devices andsystems utilizing the phenomenon of solid state luminescence under theexcitation of cathode rays have not heretofore been completelysatisfactory because of the ditficulty in obtaining high intensityimages therefrom without the use of excessively high beam currents. Thelow efliciency of luminescence obtainable from cathode ray stimulatedsolidluminescent bodies has long stood as an obstacle to the developmentof practical and efiicient information portraying devices and systemsutilizing such light emitting solids.

This difficulty is due, in part, to the fact that, in presentdayinformation portraying devices and systems in which a solid body isexcited to luminescence by radiant energy, the cathode rays energy mustnot only carry the information to the light emit-ting body, but mustalso supply the energy to that body to cause the emission oflighttherefrom. Due to this mode of operation, it is impossible to obtainhigh brightness images from cathode ray excited luminescent materialswithout irradiating these materials with electrons of such high energiesthat the use of such devices and systems is ineflicient and oftenprohibitive. a

Accordingly, it is an object of the invention to obtain high intensityluminescent images from cathode ray irra diated luminescent solids. a

A further object of the invention is to obtain high intensity visiblelight images from solid state luminescent materials irradiated by lowintensity information containing cathode rays. a I

A further object of the invention is to provide information containingcathode ray information portraying devices and systems in which agreater amount of energy is obtained from the luminescent screen than isincident thereupon.

A further object of the invention is to brightness cathode ray tube.

Briefly stated, one embodiment of my invention comprises a cathode raytube including a phosphor screen comprising a continuous, homogeneous,cathodoelectroluminescent phosphor layer disposed between, and incontact with, two conducting electrodes, at least one of which is lighttransmissive. A source of unidirectional potential is applied to the twoconducting electrodes and information-containing cathode rays aredirected upon the cathodoelectroluminescent phosphor from a suitablesource. When the cathodoelectroluminescent phosphor layer is subjectedto information-containing cathode rays, and a unidirectional voltage isapplied between opposite surfaces thereof, an amplified visible image isobtained by the luminescent emission thereof. Since the energy requiredto produce this image is derived from the unidirectional voltage sourcerather than from the incident provide a high cathode rays, the lightemitted by the cathodoelectroluminescent screen may contain greaterenergy than the incident cathode rays. Thus, an energy gain may beobtained utilizing cathodoelectroluminescence. As a result, thebrightness of light emitted by the cathode ray tubes of the invention ismuch greater than that obtainable from conventional cathode ray tubes.Cathodoelectroluminescence may be defined as luminescence controlled bycathode rays and powered by a unidirectional electric field.

In accord with another feature of the present invention a furtherincrease in the intensity of light obtained from a cathode ray andunidirectional field excited screen is obtained by simultaneouslyirradiating the screen with ultra-violet light.

The novel features believed characteristic of the invention are setforth with particularity in the appended claims. The invention itself,however, both as to its organization and method of operation, togetherwith further objects and advantages thereof, may best be understood byreference to the following description taken in connection with theattached drawings in which:

FIG. 1 shows a cathode ray tube illustrative of one embodiment of myinvention;

FIG. 2 is a graphical representation of the enhanced emission of certaincathodoelectroluminescent phosphors which may be used in constructingthe device of FIG. 1; and

FIG. 3 illustrates an alternative embodiment of the invention.

In FIG. 1 a cathode ray tube illustrative of one embodiment of theinvention is represented generally as 1. Tube 1 includes an evacuableenvelope having a conical section 2 and a neck portion 3. Within neckportion is a cathode gun 4, a modulating electrode 5 and a set ofdeflection plates 6. Cathode rays impinge upon faceplate 7 upon whichthere is located a cathodoelectroluminescent phosphor layer 8 sandwichedbetween a pair of continuous conducting electrodes 9 and 10. A source ofunidirectional potential, represented generally by battery 11 isconnected to impress a uniform unidirectional voltage transverselyacross the entirety of layer 8 by means of electrodes 9 and 10.

A beam of electrons is generated by electron gun 4 and modulated so asto contain information or intelligence by control electrode 5 to whichsignal energy is supplied by video output circuit 12. The modulatedelectron beam is swept in a raster pattern by deflection plates 6 whichare supplied a sweep signal by sweep generator 13. A raster pattern isthus impressed upon cathodoelectroluminescent layer 8 throughelectron-permeable layer 10. cathodoelectroluminescent layer 8 isexcited to luminescence and a visible image is viewed through lighttransmissive layer 9 and faceplate 7.

Conducting layer 9 may conveniently comprise any visible-lighttransmissive, conducting layer such as tin oxide, but is preferably athin layer of reduced titanium dioxide. Conducting layer 9 may be formedupon base plate 3 by the chemical reaction in a closed chamber, betweentitanium tetrachloride and water vapors which are brought into admixturewith one another in close juxtaposition to the plate while the latter isheated to approximately C. to 200 C. Film 9 may have a thickness ofabout .1 to 1 micron, but its thickness is not critical and may be asthin as is compatible with good electrical conductivity or as thick asis compatible with reasonable visible light transmissivity. Asdeposited, titanium dioxide layer 9 is not highly conductive but may berendered con ducting by the subsequent deposition thereupon of acathodoelectroluminescent layer, or may be rendered conducting by themethod -disclosed and claimed in US. Patent No. 2,717,844 to L. R.Koller.

cathodoelectroluminescent phosphor layer 8 may be any luminescentphosphor which exhibits the phenomenon of cathodoelectroluminescence.The phenomenon of cathodoelectroluminescence may be briefly described asthat'property of certain phosphors which imparts to them the ability toexhibit, under the concurrent stimulation of incident cathode rays and atransversely impressed uniform unidirectional electric field, applied byelectrodes in direct contact with opposite surfaces of a phosphor layerso that charge transport may occur therethrough, light emission which isof a high intensity greater than that obtainable utilizing cathode raybombardment alone and which may contain greater energy than, thecontrolling cathode rays. The phenomenon of cathodoelectroluminescence,which I have discovered, derives its efficiency from the principle thatthe energy which is responsible for the luminescent emission from thecathodoelectroluminescent layer is derived from the electric fieldimpressed upon the cathodoelectroluminescent layer, While light emissionis initiated and controlled by the incident cathode rays. The incidentinformation-containing cathode rays need supply only sufficient energyto the cathodoelectroluminescent phosphor to initiate and controlcathodoelectroluminescent emission, and need not supply the energyrequired to sustain the emission. In the operation of the screens of theinvention, the energy of the incident cathode rays may be quite low, butnevertheless cause high intensity light to be emitted fromcathodoelectroluminescent layer 8.

In order to describe adequately the characteristics of phosphors whichexhibit the phenomenon of cathodoelectroluminescence, the phenomenonwill be described and the characteristics necessary in order that thephenomenon exist will be set forth. Cathodoelectroluminescence is aprocess which depends, for its operation, upon the principle or photongeneration and multiplication Within phosphor layer 8. When acathodoelectroluminescent layer, such as layer 8, is in contact withapair of conduct ing electrodes, one of which is preferably metallic andat least one of which is permeable to incidient cathode rays, a uniformelectric field is established within the phosphor layer which istransverse thereto. When incident cathode rays fall upon thecathodoelectroluminescent layer, the already-existing electric fieldexisting in the vicinity of the cathode, or negatively maintainedelectrode, is increased due to the formation there of a space charge byelectrons originally bound to the crystal lattice, but freed by incidenthigh energy electrons. This increased electric field in the vicinity ofthe cathode results in the injection of a large number of free electronsfrom the metallic cathode into the cathode-adjacent region of thephosphor layer. These injected electrons are then transported throughthe phosphor layer under the acceleration of the electric field toexcite activator centers within the phosphor, causing the release of amuch greater number of photons of radiant energy than are released bycathode ray bombardment alone. Thus,

in cathodoelectroluminescence, an actual charge transport or currentflow occurs through the phosphor film. This current is increased by thecreation of electron avalanches by inelastic collisions as the distancefrom the cathode increases. Cathodoelectroluminescence is therefore aphenomenon involving. a unidirectional current flow through the phosphoras is opposed to electroluminescence wherein luminescence is excited byan electric field alone with on unidirectional flow of current but onlydisplacement current which ordinarily occurs in capacitors.

In order that the current flow which is required for.cathodoelectroluminescence occur, the phosphor layer 8 must satisfyseveral requirements. First, in order that current flow occur, theremust be direct electrical contact between phosphor layer 8 and theelectrodes 9 and 10 which must be electrically continuous in order thatthe field through layer 8 be uniform. Secondly, sincecathodoelectroluminescence depends in part upon the creation of electronavalanches and charge transport through the pho'sphonthere must be acontinuity of electrical properties throughout the phosphor layer. Inother words, layer '8 must be composed entirely of phosphor ,4 ymaterial in an orderly crystalline array with no interstices. For thisreason, conventional luminescent phosphor layers in which microcrystalsof luminescent materials are suspended in powder dielectrics or aresettled out into a heterogeneous mass by conventional liquid settlingcrequivalent techniques, do not exhibit cathodoelectroluminescence.Cathodoelectroluminescence may be achieved only in phosphor layers whichare composed entirely of the luminescent phosphor utilized and which arehomogeneous, continuous, crystalline, non-granular and exhibit uniformelectrical properties throughout. If, for example, the electricalproperties throughout the phosphor are not uniform, charge transport maynot occur and cathodoelectrolunilinescence may not be observed.

Layers of phosphor which may be utilized in the creation ofcathodoelectroluminescent intensifying cathode ray tubes in accord withthe invention may be prepared by chemically reacting the vaporscontaining phosphor constituents and a selected activator in thevicinity of the substrate upon which the layer is formed to cause thecrystallization from the vapor phase of a continuous, homogeneous,crystalline, non granular layer composed entirely of the chosenactivated phosphor. Alternatively, phosphor layers may be formed byspraying the constituent materials upon a heated substrate to cause thechemical reaction therebetween andthe deposition thereupon of a uniform,crystalline, homogeneous activated phosphor layer. These methods offormation of phosph'or layers are disclosed in greater detail in PatentNo. 2,685,530 to Cusano and Studer. Cathodoelectroluminescentphosphor'layers may also be formed upon a suitable substrate by vacuumevaporation techniques to cause the condensation, upon a suitablesubstrate, of a continuous, homogeneous, non-granular phosphor layer. Ingeneral, any method of phosphor preparation which results in theformation of a homogeneous, continuous, non-granular phosphor layer upona suitable substrate is suitable. The phenomenon ofcathodoelectroluminescence may be observed with members of thezinc-cadmium. sulfoselenide family including zinc sulfide, cadmiumsulfide, zinc selenide, cadmium selenide, or mixtures thereof such aszinc-cadmium sulfide, zinc-cadmium. selenide, cadmium sulfo-selenide,zinc-cadmiurn-sulfo-selenide and zinc sulfo-selenide, activated withmanganese, arsenic, phosphorus or antimony and a halogen, or one ofthese phosphors activated with two or more of the foregoing activators ahalogen.

If manganese is utilized as the principal activator for phosphorlayer 8,the manganese should be present in proportions from 0.1 to 5% by weighttogether with 0.1 to 5% by weight of a halogen preferably chlorine. Ifarsenic, phosphorus or antimony are utilized as the principal activatorin the devices of the invention, these materials should be present inproportions of from 0.01 to 1% Weight ofphosphorus, arsenic or antimony,together with 0.01 to 1% by weight of a halogen, preferably chlorine.While chlorine is preferably the halogen used, other halo-gens such asbromine and iodine may be used as well in thesame proportions.

Although cathodoelectrolurninescent phosphor layer 8 may be prepared ina number of days, it is preferably prepared by the vapor reactiontechnique described and claimed-in U.S. Patent No. 2,685,530 to Cusanoand Studer.

As an example of this method, base plate 7, coated with a thin film 9 oftitanium dioxide, is suspended in a reaction chamber and heated to'atemperature of from 500 C. to ,700 C. but preferably to approximately620 0. man evacuated reaction chamber. A charge of materialcomprisingthe phosphor cation as for example elemental zinc, a halogen containingconstituent, .asfor example-zinc chloride, and a luminescence activatorcontaining constituent, as for example, manganese chloride, iscontinuously fed into an evaporation vessel wherein the charge isvaporized. Vapors of the phosphor cation, a halogen, and a luminescenceactivator'arise and are mixed with vapors of a gas containing thephosphor anion, as for example, hydrogen sulfide. The gas and the vaporsreactchemically at the surface of the heated base plate 5 and deposit,by vapor deposition, a thin, transparent, continuous, crystalline,non-granular, cathodoelectroluminescent phosphor layer thereupon, whichin this instance is zinc sulfide activated with manganese and chlorine(ZnS:Mn, Cl). To produce a selenide phosphor, H Se may be used.

The process of the vapor deposition of cathodoelectroluminescent layer 8is carried out at a controlled rate for..

a preselected period of time which is selected to deposit the desiredthickness layer upon base plate 7. Conveniently phosphor layer 8 may befrom 1 to 100 microns thick depending upon the energy, and hence, thepenetrating power of the cathode rays utilized. For cathode raysaccelerated through a potential of 15 kilovolts, a layer thickness ofapproximately 1 to 10 microns is utilized.

In one specific example of the formation of a cathodoelectroluminescentimage presentation device in accord with the invention, a Pyrex glassbase plate approximately 3 inches in diameter having thereon a severaltenths micron thick layer of titanium dioxide was suspended in anevacuated reaction chamber and heated by an external heater to atemperature of approximately 620 C. A flow of hydrogen sulfide into thereaction chamber was initiated to establish therein an atmosphere ofhydrogen sulfide at approximately 1 millimeter of mercury pressure. Acharge consisting of grams of zinc, 12.5 grams of zinc chloride and 0.50gram of manganese chloride is slowly and continuously fed into thereaction chamher and evaporated in the evaporation vessel which ismaintained at a temperature of 680 C., the introduction of the chargebeing spaced over a period of minutes. The vapors of the charge reactwith the hydrogen sulfide gas over the 30 minute period to deposit uponthe titanium dioxide coated glass base plate a film of manganese andchlorine activated zinc sulfide approximately 10 microns thick.

Upon the deposition of the zinc sulfide cathodoelectroluminescentphosphor layer upon the glass base plate, the titanium dioxide film,which originally is non-conducting, is lowered in resistivity to a valueof approximately 1000 ohms per square. This value is very small ascompared with the resistvity of cathodoelectroluminescent phosphor layer8, and enables the titanium dioxide film to be utilized as an electrodeas hereinbefore described. A thin aluminum layer 10 approximately 0.1micron thick is then evaporated on layer 8, and the faceplate assemblyis assembled in cathode ray tube 1.

In another specific example of the information of thecathodoelectroluminescent presentation tube, the same ap paratus as usedin the previously described example is utilized, the titanium dioxidecoated base plate is maintained at a temperature of 600 C. and thereaction chamber is maintained in an atmosphere of hydrogen sulfide at600 microns pressure. A layer 10 microns thick is deposited upon a 6"diameter Pyrex glass plate by continuously feeding into the evaporationboat over a period of 30 minutes a mixture consisting of 4.5 grams ofred phosphorus, 25 grams of zinc chloride, and grams of powderedmetallic zinc. A 0.1 micron layer of aluminum is evaporated on thislayer and the faceplate assembled into a cathode ray tube.

In another specific example, a 1-0 micron thick layer is formed upon a6" diameter titanium dioxide coated Pyrex glass plate maintained at atemperature of 600 70 C. in an atmosphere of 600 microns of hydrogensulfide .While a mixture consisting of 1.13 grams of arsenic, 25 gramszinc chloride and 50 grams of metallic zinc was fed into the evaporationboat over a period of 30 minutes. In another specific example, a 20micron thick layer 6 is formed on a 6" diameter titanium dioxide coatedI yrex glass plate maintained at a temperature of 600 C. in anatmosphere of 600 microns of hydrogen sulfide gas while a mixtureconsisting of 2.25 grams of antimony, 25 grams of zinc chloride, and 50grams of powdered metallic zinc was fed into the evaporation boat over a30 minute period.

In another specific example, a 20 micron thick layer was formed upon a6" diameter titanium dioxide coated Pyrex glass plate maintained at atemperature of 600 C. in an atmosphere of 600 microns of hydrogensulfide gas while a mixture consisting of 0.25 gram. of manganesechloride, 2.25 grams of red phosphorus, 25 grams of zinc chloride, and50 grams of powdered metallic zinc was fed into the evaporation boatover a period of 45 minutes.

In another specific example, a 20 micron thick layer was formed upon a 6diameter titanium dioxide coated Pyrex glass plate maintained at atemperature of 600 C. in an atmosphere of 600 microns of hydrogensulfide while a mixture consisting of 0.25 gram of manganese chloride,1.13 grams of arsenic, 25 grams of zinc chloride and 50 grams ofpowdered metallic zinc was fed into the evaporation boat over a periodof 45 minutes.

In another specific example, a 20 micron thick layer was formed upon a 6diameter titanium dioxide coated Pyrex glass plate maintained at atemperature of 600 C. in an atmosphere of 600 microns of hydrogensulfide gas while a mixture consisting of 0.25 gram of manganesechloride, .70 gram of antimony, 25 grams of zinc chloride and 50 gramsof powdered metallic zinc was fed into the evaporation boat over a 45minute period.

In the above examples after the deposition of phosphor layer 8, asdescribed above, a thin coating of a suitable conducting material 10having a sufiiciently small thickness as to be penetrable or transparentto the incident cathode rays is applied over the phosphor layer.Conveniently, conducting layer 10 may comprise an easily volatilizablemetal, as for example, aluminum, silver or gold. When such metals areused the thickness is chosen to result in little energy loss to theincident cathode rays and may be approximately 0.1 micron thick for a 15kilovolt electron beam. Such metals may be deposited by well knownmethods, as for example by vacuum evaporation or sputtering. Theassembly of face plate 7 and layers 9, 8, and 10 is then assembled intoa cathode ray tube as illustrated in FIG. 1.

To achieve intensified images in operating tube 1, the average fieldstrength established within layer 8 should be approximately 10 to 10volts per centimeter. Battery 11 is connected with transparentconducting film 9 positive, and metallic conducting film 10 negative.For 5 to 30 kilovolt electron beams, wherein thecathodoelectroluminescent film may conveniently be 10 microns thick,voltage source 11 may supply approximately 10 0 volts. For higher energybeams, cathodoelectroluminescent layer 8 may be thicker and battery 11may conveniently supply a higher voltage.

Unlike cathodoluminescent and electroluminescent phosphors whichgenerally utilize other activators than are utilized in thecathodoelectrolurninescent phosphor layers of the invention, and aregenerally of the suspended phosphor powder in dielectric type,cathodoelectroluminescent phosphor layer 8 displays only weakluminescence with the application of the electric field thereto, in theabsence of incident cathode rays. This has been found to be true forvalues of field strength as high as approximately 10 volts percentimeter. The same phosphor layer is brought to only weak luminescencewhen scanned by impinging information-containing cathode rays; Thisluminescence, as is well known, always possesses less energy than thekinetic energy of the in cident cathode rays. When, however, aunidirectional field of the proper polarity, as described above, isimpressed upon the cathodoelectroluminesc-ent phosphor layer, thebrightness of this weak luminescent image is 1 7 substantiallyincreased,.and is observed to increase by a factor of as much as anorder of magnitude over the intensity of the image produced by anelectron beam alone; Under the proper conditions the energy emitted bythe phosphor layer can be greater than the kinetic energy of theexciting cathode ray beam.

FIG. 2 of the drawing illustrates the increased brightness obtainablefrom cathode ray tubes constructed in accord with the present invention.The curve of FIG. 2 is a plot of the ratio of brightness of the lightemitted from the device of FIG. 1 with battery 11 connected to thebrightness of the device with battery 11 disconnected as a function ofbeam current density. The ratio expressed is, therefore, the ratio ofbrightness obtained from a device constructed in accord with the presentinvention to brightness obtained from a conventional cathode ray tube ofsimilar construction. As may be seen from FIG. 2, tubes constructed inaccord with the invention show up to 11 times the brightness exhibitedby conventional cathode ray tubes at low current densities.

cathodoelectroluminescent image intensification att ained inthe devicesof the present invention, is to be distinguished from various transienteffects such as the Gudden-Pohl or Lenard effects in which momentaryenhancement of luminescence is attained by the application to, orremoval of, an electric field from a luminescent phosphor. Suchphenomena. depend upon the effects of storage of electrons at trappingenergy levels, and are transient in nature only.Cathodoelectroluminescence, on the other hand, is a steady statephenomenon which results in the continuous intensification ofcathodoluminescentinforrnation and images.

It may readily beseen, therefore, that the cathodoelectroluminescentetfects of the invention are neither simple electroluminescent effectsnor simple cathodoluminescent effects, but rather, dependent upon theconcurrent excitation of certain phosphors by cathode rays and anapplied undidir-ectional electric field. As mentioned hereinbefore,since the applied electric field supplies the energy to produceluminescence, and the incident cathode rays trigger and control thisluminescence, a potentially greater amount of energy is derived from thescreens than is incidentthereupon in the incident cathode rays.

A further embodiment of the invention is illustrated diagrammatic-allyin FIG. 3 of the drawing. In FIG. 3 cathode ray tube '1 as illustratedin FIG. 1 is similarly connected and a unidirectional electrical fieldsupplied to cathodoelectroluminescent layer 8 by means of unidirectionalvoltage source 11. Cathodoelectroluminescent layer 8 is furtherirradiated with a uniform intensity of ultra-violet from ultra-violetsource 14. In this embodiment of the invention, thehereinbefore-discussed increase in the brightness of luminescent imagesobtained from cathodoelectroluminescent layer 8 may be achievedutilizing greater thickness cathodoelectroluminescent layers than may beutilized in the embodiment of FIG. 1. In the embodiment of FIG. 1 theenhancement of the brightness light output is dependent upon thepenetrating power of the cathode rays for the creation of the initialfree electrons which eventually excite the phosphor to luminesce. Thepenetrating power of these electrons is not too great in extremely thickluminescent films. For mechanical properties, however, it may bedesirable that thicker films be utilized. According to this alternativeembodiment of the invention, therefore, I utilize a very thickcathodoelectroluminescent layer as, for example, from to 100 micronsthick and obtain luminescent images therefrom utilizing relatively lowelectron beam velocities as, for example, 25 kilovolts by simultaneouslyimpressing a unidirectional electron field upon thecathodoelectroluminescent layer and likewise. simultaneouslyirradiating: the. cathodoelectroluminescent layer 8 through transparentconducting; layer 9 with a uniform intensity of ultra-violet as forexample 3650 8 A.U. wavelength light. cathodoelectroluminescent layerwith ultrawibl'et. so de;

creases the resistivity thereof, that the low voltage .el'ec trons canmuch more radically increase space cha'rg,.

thus facilitating the production of greatlyenhancdcathodoelectroluminescent images from thickcathodoelectroluminescent films utilizing moderately low cathode rayenergy beams.

While I have described above certain specific embodi ments of myinvention, many modifications and changes will immediately occur tothose skilled in the art. It

will be appreciated, therefore, that by the appended claims I intend tocover all such modifications and changes as fall within the true spiritand the scope of the foregoing disclosure.

What I claim as new and desire to secure. by Letters Patent of theUnited States is:

1. A high brightness cathode ray intensifying device comprising: anevacuable envelope having at one end' thereof a luminescent screen, saidscreen including only a phosphor layer consisting entirely ofcathodoelectroluminescent material which is continuous, crystal-line,homogeneous and nongranular and a pair of conducting electrodescontacting opposite surfaces of said cathodoelectroluminescent phosphor,at least one of'said electrodes being electron permeable; and means atanother end of said envelope for generating, modulating, focusing anddeflecting a beam of cathode rays over said screen to directly irradiateand excite said phosphor layer. and

initiate emission therefrom.

2 A high brightness cathode ray image intensifying device comprising: anevacuable envelope having a face, plate at one end thereof; atransparent conducting layer deposited upon said face plate; a phosphorlayer deposited upon said transparent conducting layer, said phosphorlayer being composed only of cathodoelectroluminescent phosphor materialwhich is continuous, crystalline,,homogerreous and nongranular; anelectrically conductive electron permeable layer deposited over theexposed surface.

of said cathodo -electroluminescent phosphor layer; and. means atanother end of said envelope. for generating,

focusing, modulating and deflecting a beam of cathode rays over saidface plate which directly irradiate said: phosphor layer.

3. A high brightness cathode ray intensifying device comprising: anevacuable envelope having a face plate, at one end thereof; a phosphorlayer disposed adjacent said face plate, said phosphor layer consistingonly of a cathodoelectroluminescent phosphor which is continuous,crystalline, homogeneous and nongranular; a pair of con ductingelectrodes in contact with opposite surfaces of said layer so as todirectly contact the cathodoelectroluminescent phosphor, at least one ofsaid electrodes being electron permeable; and means for impressing auniform unidirectional electric field transversely across said phosphorlayer.

4. A high brightness cathode ray image intensifying device comprising anevacuable envelope having a face plate at one end thereof; a transparentconducting layer deposited upon said face plate; a phosphor layerdeposited upon said transparent conducting layer, said phosphor layerconsisting only of a cathodoelectroluminescent phosphor which iscontinuous, crystalline, homogeneous and nongranular; an electricallyconductive, electron permeable layer deposited over the exposed surfaceof said cathodoelectroluminescent. phosphor layer; means at another endof said envelope for generating, focusing, modulating and deflecting abeam of cathode rays oversaid face plate to directly irradiate andexcite said phosphor layer and initiate emission therefrom; andmeans.for impressing a uniform unidirectional electric field transverselyacross said phosphor layer.

5. Av high brightness; cathode ray intensifyingv device comprising anevacuable envelope having a faceplate at one end thereof; a phosphorlayer disposed adjacent The irradiation of the thick;

said face plate, said phosphor layer being composed only of acathodoelectroluminescent phosphor which is transparent, continuous,homogeneous and nongnanular and selected from the group consisting ofthe sulphides and selenides of zinc, cadmium and mixtures thereofactivated with a halogen and a material selected from the groupconsisting of manganese, arsenic, antimony and phosphorus; and a pair ofelectrically conductive electrodes directly contacting opposite surfacesof said phosphor layer so as to directly contact thecathodoelectroluminescent phosphor, at least one of said electrodesbeing electron permeable; and means at another end of said envelope forgenerating, modulating, focusing and deiflecting a beam of cathode raysover said face plate to directly irradiate said phosphor layer andinitiate emission therefrom.

10 6. The device of claim 5 wherein the phosphor is zinc sulfideactivated with manganese and chlorine.

References Cited in the file of this patent UNITED STATES PATENTS2,675,331 Cusano Apr. 13, 1954 2,780,731 Miller Feb. 5, 1957 2,792,447Kazan Mar. 14, 1957 2,859,367 Larach Nov. 4, 1958 2,863,084 Arnott Dec.2, 1958 2,881,353 Michlin Apr. 7, 1959 2,892,096 Kruse June 23, 19592,915,661 Lederer Dec. 1, 1959

